Collapsible boat



1945- F. B. s. GRIMSTON COLLAPS IBLE BOAT Filed July 28, 1945 5 Sheets-Sheet l K O T N E v N A S 6mm: SYLvEsTER GR M Feb.27, 1945. Bi gIM QN 2,370,401

COLLAPSIBLE BOAT Filed July 28, 1943 5 Sheets-Sheet 2 W WWL 41 M V.

Feb. 27, 1945. F. B. s. GRIMSTON COLLAPS IBLE BOAT Filed July 28, 1945 5 Sheets-Sheet 3 m FRANCISBRMNSYLVESTEK fimmsTou mvEm-Q Oflb L Feb. 27, 1945. F. B. s. GRIMSTON COLLAPSIBLE BOAT Filed July 28, 1943 5 Sheets-Sheet 4 FRANUS BRIAN SvLvesT RfiRmaT u NVEN Tom Feb. 27, 1945. F. a. s. GRIMSTON 2,370,401

COLLAPSIBLE BOAT I Filed July 28, 1943 5 Sheets-Sheet my. '18.

RIAN SY LVE sTEra @Rlmsmu N V E NTOK EAN ig B Patented Feb. 27, 1945 COLLAPSIBLE BOAT Francis Brian Sylvester Grimston, Farnham Royal. England Application July 28, 1943, Serial No. 496,381

. In Great Britain July 30, 1942 28 Claims.

This invention relates to collapsible boats.

An object of the invention is to provide an improved construction of such boats, which is applicable to various kinds of boats and also to sectio s of sectional collapsible boats, and which enables the boat, when not in use, to be knocked down and packed substantially flat, while erection of the parts can be carried out easily. The term collapsible boat, where the context allows, is to be read hereinafter as including a section of a sectional collapsible boat.

A further object is to provide a collapsible boat which, when erected, is strong enough to carry an outboard motor and the lines of which will enable it to be propelled thereby safely at a substantial speed.

Another object is to provide a collapsible boat in which the essential elements are connected together when the boat is in the knocked-down condition and which can, if necessary, be erected under dimcult conditions, for example, when afloat.

Another object is to provide in a collapsible boat a skin having such mechanical properties that it will assume in the erected boat a compound curvature by virtue of its inherent stillness.

Another object is to provide a collapsible boat having substantial buoyancy when in the knocked-down condition.

Another object is to provide a rigid deck frame, which may be partly covered by decking if desired, and a rigid transom which is permanently connected to a floor member of the boat and to the deck frame.

Another object is to provide an arrangement for forming a stem of the boat While avoiding undesirably sharp curvature of the skin under the bottom of the stem and ensuring a watertight seal.

Another object i to provide convenient operatin means whereby the boat can be erected single-handed and automatically locked in its erected condition and as easily' restored to the knocked-down condition.

An embodiment of the invention as applied to a dinghy constructed of wood will be described by way of example with reference to the accompanying drawings, in which: 7

Figs. 1, 2 and 3 are perspective views of the boat erected, in course of erection or knocking down, and completely knocked down, respectively.

Fig. 4 is a composite plan, the upper half showing the deck frame and the lower half the rigid floor member.

Fig. 5 is a sectional Side elevation of the erected boat,

Figs. 6, 7 and 8 are respectively sections on the lines 6--6, 1-7 and 8-8 of Fig. 5,

Fig. 9 is a transverse section of one side of the deck frame and the gunwale stringer in the erected boat, showing locking means,

Fig. 10 is a diagrammatic side elevation of the stem of the erected boat,

Figs 11, l2, l3 and 14 are respectively diagrammatic sections on the lines H-Il, |2-l2, l3l3 and 14-14 of Fig. 10,

Figs. 15 and 16 are diagrammatic plans of the layout of the straining cable in the knockeddown and in the erected boat respectively.

Fig. 17 is a perspective view of an alternative construction of stem partly assembled,

Fig. 18 is a view of skin reinforcement for use in this alternative construction,

Figs. 19 and 20 show the same construction at later stages in assembly,

Fig. 21 shows an extension nose piece for use in the same construction, and

Fig. 22 is a longitudinal vertical section showing the complete assembly erected.

The rigid floor member, generally denoted by 20 (Figs. 4, 5 and 6), is an isosceles triangle in plan, the base being at the stern. It consists of two straight stringers 2| defining the equal sides of the triangle, a nose piece 24 at the bow, and transverse rails 22A, 223, etc., these frame'elements being covered by a fiat sheet 23 having lateral extensions 23A serving as support for seat cushions.

The skin 25 is in one piece, secured to the under side of the floor frame members, the spaces between the floor sheet 23 and the skin 25 forming buoyancy chambers I 28. The skin 25, when seen flat in plan view, is rectangular at the stern, and its side edges are substantially parallel for the greater part of the length towards the bow where they curve towards each other, as shown in Figs. 3 and 15. The front edge of the skin is provided with a shallow V notch 26, the sides of which are reinforced by stem posts 2'! fixed to the inner side of the skin and of a length corresponding to the stem of the'erected boat. The bottom of the V notch 26 merges into a partcircular recess 28 (Figs. 10, 11 and 12) concentric with the point of intersection of the projected sides of the notch. The longitudinal borders of the skin are reinforced with flexible gunwale stringers 29.

At each side of the stem end of the fiooris a rigid lateral extension 30 having a. depth equal to the thickness of the adjacent end of the floor and shaped to impart the desired form to the skin between the bottom of the floor and the transom when the boat is erected. These extensions are faced with sealing strips of rubber, arranged similarly to the strips 43 shown in Fig. 8. A rigid transom 3] is hinged to the stem end of the floor and to the extensions 30 in such a manner that it can fold forwards and lie flat against the floor, its side edges being provided with sealing strips 43 Of rubber (Fi 8) A transverse frame formed of two V shaped 'braces 92 rigidly connected together by a bar 92 (Figs. 3, 5 and 6) is similarly hinged to the floor near the bow.

A deck frame 99, conforming in outline to the top plan of the boat, is hinged at 24 to the transom II and at 25 to the transverse braces 92. so that the deck frame can move relatively to the floor rather after the manner of the elements of a parallel ruler, except that on erection of the boat the fore part of the deck frame is raised higher than the after part above the floor. The deck frame, the fore part which is covered by decking 36, consists of gun' ale stringers 31 and a cockpit coaming '38 tied together by a prow block-39, transverse bars 40A, 40B and 49C, and spac g blocks A, B etc. The lower borders of t outer sides of the deck frame stringers 31 are rovided with bevels 42 for engagement by the up r borders of the skin 25 when the latter is ben up into the erect position.

The stem is reinforced by flexible sheet-metal reinforcement 44 (Figs. 1 and 10-14) fixed to the outer surface of the skin and covering the recess 28. Sealing of the stem is effected by a continuous rubber strip 45 fixed to the inner faces of the stem posts and passing between the floor nose piece 24 and the skin reinforcement sheet 44.

In order to ensure that the lower ends of the stem posts 21 are locked together and to the nose piece 24 when the boat is erected, .two plates 46 are fixed to the rear facesof the respective stem posts and provided with hook-like projections 41 .shaped to engage, as the boat is being erected,

over two pins 48 projecting from the rear faces of an upward extension 24A of the nose piece 24, the arrangement being such that, as the upper ends of the stem posts are drawn together in a manner to be described hereinafter, the projections 41 hook automatically over the pins 49 and act as levers forcing the lower ends of the stem posts towards eachother and drawing the skin reinforcement 44 taut round the nose piece against the sealing strip 45.

In order to facilitate erection of the boat, a telescopic strut 49 is pivotally connected between the floor nose piece 24 and the deck frame cross member 490. This strut is arranged to lock automatically in its extended condition, by means of a spring catch 50 mounted in the inner -mem-, ber of the strut and adapted to lock in a slot in the outer member when the deck frame has been raised to its erected position. Furthermore, the deck frame, the skin and the transom are connected by a running cable operated by a winch (Fig. 5) carried by the decking with its drum 52 on the under side and a capstan wheel 63 on the upper side. The capstan wheel has ratchet teeth 64 co-operating with a spring-loaded pawl 65 provided with a release trigger 99. The cable 5i (Figs. 3, 15 and 16) is looped symmetrically, with both ends anchored to the winch drum. Starting from one end at the drum, the cable is returned around a guide pulley A on the under side of the deck near its starboard edge and passes thence to a pulley B mounted on the inner side of the skin adjacent to the upper end of the port side stern post 21. The cable next crosses to a pulley C mounted on the inner side of the skin near its upper edge on the starboard side at about one-third of the length of the deckfrom the stem. From the pulley C the cable passes round a pulley D on the under side of the deck frame at the starboard side and thence along the same side past a guide pulley E and round a pulley F, whence it is led through the skin to a pulley G mounted on the under side of the gunwale stringer II (Fig. 9). The cable runs thence towards the stern outside the skin, passes round a pulley H, mounted also on the under side of the gunwale stringer, and returns through the skin to a pulley J in the transom. The cable lies freely across the transom, its return run being a mirror copy of the run so far described.

Bolts 91 (Figs. 3 and 9) are anchored in the gunwale stringers 29 adjacent respectively to the pulleys B, C, G and H and project normally from the inner surface of the skin. These bolts are adapted, on erection of the boat, to engage in locating apertures 68 opening at the bevelled surface 42 of the deck frame. The bolts 61 are tapered, and they can pass through to the inner side of the deck stringers 9|. Latches i9, mounted on the inner side of the stringers 3|, are adapted to engage in notches III in the bolts when the latter are fully home. The eight latches 69 may be connected for release simultaneously by a cable (not shown) leading to a control lever adjacent to the winch drum.

The skin 25 is composed of three-ply resinbonded plywood A; in. thick in the example shown, which is approximately 12 ft. long over all when erected. This material tends to recover its flat sheet form when free, and, when the boat is erected, it assumes a compound curvature, i. e. it is curved in both plan and end views, and is therefore stout enough to be self-supporting in the absence of transverse frames or ribs. Alternatively the skin may be a resin-bonded sheet composed of alternate laminations of wood and fabric.

In erecting the boat from its knocked-down condition shown in Fig. 3, first the deck frame is pulled upwards and rearwards until the tele-. scopic strut 49 locks in its extended condition, the transom now being upright. Thereafter the winch is operated to tighten the cable 5i, the arrows in Figs. 15 and 16 showing the direction of rotation of the winch drum and the direction of movement of the cable. The skin is consequently bent upwards until its longitudinal borders abut against the bevel 42 on the deck frame. the bolts 61 passing through the locating apertures 68 and'depressing the latches 99, which finally engage in the notches I0 as the winch completes its operation.

Even if the boat is put afloat in its knockeddown condition, the buoyancy of the floor is such that it will support a man while he erects it, the boat thereafter being bailed or pumped dry at leisure.

The boat can be knocked down by releasing the winch ratchet and the latches 69, and thereafter unlocking the strut 49 and pressing the deck downwards and forwards. The winch ratchet and the latches may be provided with a common releasing control.

This example of the improved boat is a sturdy. seaworthy craft, capable of planing when fitted with an outboard motor, and of being safely beached on shingle. It is therefore a serviceable dinghy for ordinary use, and is particularly suitable for stowing on or against the superstructure of a ship or smalled craft where deck space is limited, and for carrying on a flying boat, since in its knocked-down condition it can be easily stowed against an emergency knock-out panel of the hull of the flying boat. Since the improved boat when knocked down occupies a volume which is less than one-third of the volume occupied by an erected boat, it is suitable for stowage on ships where deck space is valuable.

In order to avoid risk of damage to the skin near the bottom of the stem owing to careless handling of the boat when it is in the knockeddown condition, means may be provided for limiting downward displacement of the lower ends of the stem posts relative to the floor under these conditions.

Figs. 17 to 22 show an alternative arrangement of stem which is preferred for use in a dinghy intended for hard service, and in which the floor has a reinforced nose piece. In Fig. 17 an inner nose piece I24 is stepped at 80 so that its forward end is. raised above the general level of the rest of the under surface of the floor, the riser of the step 80 lying behind the recess 28 in the skin 25. To the front of the nose piece I24 is fixed a metal bracket 8I having two ears 82 projecting forwardly at the bottom of the front of the nose piece. Each ear has a transverse groove 83 extending part way across it. The sheet metal reinforcement I shown in Fig. 18 is shaped to engage outside the skin 25 adjoining the V notch 26 andthe recess 28, the rear edge of the reinforcement conforming to the dotted line I 44 in Fig. 17. The leading borders of the reinforcement are returned at 84 so as to engage around the edges of the skin at the V notch. A sheet 85 of rubberpreferably a sponge rubber containing completely closed voids'is fitted in the Thus, for example, another embodiment of the invention is a canoe, in which the skin is provided at each end with a stem-forming notch. In this case no deck frame is necessary, and the skin is constrained to assume the desired compound curvature on erection by interposing a suitable number of transverse struts between the gunwales and by locking the two sides of each notch together. Such a canoe may be made in two sections, each having at one end a bulkhead or a transverse frame adapted to be rigidly fixed to the corresponding member of the other section.

I claim:

1. A collapsible boat including a rigid longitudinally-extending base member, a skin of springy resilient material secured to said base member, capable, when the boat is knocked down, of lying substantially fiat and also capable of being bent up to form the sides of the hull, two

flexible gunwale stringers secured to the longitudinal borders of said skin, a transverse bracin member capable of positioning said sides when the boat is erected, and means capable, on erection of the boat, of reacting on said skin in the v neighbourhood of said gunwale stringers so as step in the manner shown in Fig. 19, and is provided with a V notch 86 conforming to the missing bottom portion of the V notch 26 of the skin. The rubber sheet is cut back at 81 on i each side of the V notch so as to lie snugly against rear faces of the stem posts I21 near their lower ends. The stem posts extend within the recess 28 and their lower ends engage over the rubber sheet 85, as shown in Fig.20. Each stem post is fitted with a projecting arm I41 adapted when the boat is erected to engage the adjacent groove 83 of the nose piece so that the lower ends of the stem posts are tied together. Furthermore, when the boat is knocked down, the arms I41 still project over the ears 82 and so prevent undue downward displacement of the front part of the skin relative to the floor. The stem posts I21 are of angle section and accommodate a sealing strip of rubber I45, which is shown broken in Fig. 20, but which is in fact cbntinuous across the V notch, as indicated by the -ehain"-dotted lines.

An extension nose piece I24A of metal (Fig. 21) is finally fitted to the inner nose piece I24 so as to embrace the rubber sheet 85 and the sealing strip I45, as shown in Fig 22. The extension nose piece has a sole plate 88, which is provided with a central rib 89 forming the fore end of a keel stringer 9D, and which is fitted outside the hull, and an upper plate 9| which is fixed down onto the nose piece I24. A shank portion 92 of the extension nose piece I24A, under which the rubber elements 85 and I45 are looped when theboat is erected, is so shaped as to keep these elements firmly nipped between the sheet metal reinforcement I44 and the nose. The rubber sheet 85 serves to prevent leakage of water between the reinforcement and the end of the stem post I21 projecting into the recess28 and also any leakage which may tend to occur between the stem posts and the skin and between the reinforcement and described as applied to a dinghy, it will be evident that it is applicable to other kinds of boats.

to curve them as viewed in plan and at the same time strain the skin inwards into engagement with said transverse bracing member, said skin having such mechanical properties that it will assume in the erected boat a compound curvature by virtue of its inherent stiffness.

2. A collapsible boat including a base member.

consituted by a substantially flat floor having at least one buoyancy chamber, a skin of springy resilient material secured to said base member, capable, when the boat is knocked down, of lying substantially fiat and also capable of being bent up to form the sides of the hull, two flexible gunwale stringers secured to the longitudinal borders of said skin, a, transverse bracing member capable of positioning said sides when the.

boat is erected, and means capable, on erection of the boat, of reacting on said skin in the neighbourhood of said gunwale stringers so as to curve them as viewed in plan and at the same time strain the skin inwards into engagement with said transverse bracing member, said skin having such mechanical properties that it will assume in the erected boat a compound curvature by, virtue of its inherent stiffness.

3. A collapsible boat including a rigid longitudinally-ext'encling base member, a skin of springy resilient material secured to said base member, capable, when the boat is knocked down. of lying substantially fiat and also capable of being bent up to form the sides of the hull, two flexible gunwale stringers secured to the longitudinal borders of said skin, a rigid deck frame capable of positioning said sides when the boat is erected, and means capable, on erection of the boat. of reacting on said skin in the neighbourhood of said gunwale stringers so as to curve them as viewed in plan and at the same time strain the skin inwards into engagement with said deck frame, said skin having such mechanical properties that it will assume in the erected boat a compound curvature by virtue of its inherent stiffness.

4. A collapsible boat including a rigid floor, a rigid deck frame, a rigid transom, hinge means connecting said transom permanently to said fioor and to said deck frame, a skin of resilient material extending laterally from each side of said fioor, and means for securing the longitu dinal borders of said skin to the longitudinal edges of said deck frame.

5. A collapsible boat including a rigid floor, a rigid deck frame, a rigid transom hingedly connected to said floor and to said deck frame, a rigid transverse frame, disposed inthe fore part of the boat and hingedly connected to said floor and to said deck frame, the arrangement being such that said deck frame can be collapsed onto said floor after the manner of a parallel ruler, a skin of resilient material extending laterally from each side of said floor, and means for se curing the longitudinal borders of said skin to the longitudinal edges of said deck frame.

6. A collapsible boat including a rigid floor, a rigid deck frame, a rigid transom hingedly connected to said floor and to said deck frame, a rigid transverse frame, disposed in the fore part of the boat and hingedly connected to said floor and to said deck frame, the arrangement being such that said deck frame can be collapsed onto said floor after the manner of a parallel ruler, a telescopic strut which is pivotally connected between said deck frame and said floor and which serves when extended to lock said deck frame in the erected relationship with respect to said floor, a skin of resilient material extending laterally from each side of said floor, and means for securing the longitudinal borders of said skin to the longitudinal edges of said deck frame.

7. A collapsible boat including a substantially flat rigid floor, a skin of springy resilient material secured to said floor, capable, when the boat is knocked down, of lying substantially flat and also capable of being bent up to form the sides of the hull, two flexible gunwale stringers secured to the longitudinal borders of said skin, a rigid deck frame capable of positioning said sides when the boat is erected, means capable, on erection of the boat, of reacting on said skin in the neighbourhood of said gunwale stringers so as to curve them as viewed in plan and at the same time strain the skin inwards into engagement with said deck frame, and a rigid transom hingedly connected to said floor and to said deck frame, said skin having such mechanical properties that it will assume in the erected boat a compound curvature by virtue of its inherent stiffness.

8. A collapsible boat including a substantialhr fiat rigid floor, a rigid transom and a rigid transverse frame hingedly connected to said floor, a rigid deck frame hingedly connected to said transom and to said transverse frame in such a manner that said deck frame can be collapsed onto said floor after the manner of a parallel ruler, a skin of springy resilient material secured to said floor, capable, when the boat is knocked down, of lying substantially flat and also capable of being bent up to form the sides of the hull, two flexible gunwale stringers secured to the longitudinal borders of said skin, and. means capable, on erection of the boat, of reacting on said skin in the neighbourhood of said gunwale stringers so as to curve them as viewed in plan and at the same time strain the skin inwards into engagement with said deck frame, said skin having such mechanical properties that it will assume in the erected boat a compound curvature by virtue of its inherent stiffness.

9. A collapsible boat including a substantially flat rigid floor, a rigid transom and a rigid transverse frame hingedly connected to said floor, a rigid deck frame hingedly connected to said transom and to said transverse frame in such a manner that said deck frame can be collapsed forwards onto said floor after the manner of a parallel ruler, a telescopic strut which is pivotslly connected between said deck frame in the neighbourhood of the connection thereto of said transverse frame and said floor in the neighbourhood of the fore end thereof, a skin of springy resilient material secured to said floor, capable, when the boat is knocked down, of lying substantially flat and also capable of being bent up to form the sides of the hull, two flexible gunwale stringers secured to the longitudinal borders of said skin, and means capable, on erection of the boat, of reacting on said skin in the neighbourhood of said gunwale stringers so .as to curve them as viewed in plan and at the same time strain the skin inwards into engagement with said deck frame, said skin having such mechanical properties that it will assume in the erected boat a compound curvature by virtue of its inherent stiffness.

10. A collapsible boat including a skin of springy resilient material capable when the boat is knocked down of lying substantially flat and capable of being bent up to form the sides of the boat, said skin having such mechanical properties that it will assume in the erected boat by virtue of its inherent stiffness curvature as viewed in both plan and elevation at the same place, and said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which opens out into a recess so as to eliminate a sharp fold in said skin at the bottom of the stem of the boat when erected.

11. A collapsible boat including a rigid longitudinally-extending base member, a skin of springy resilient material which extends laterally from each side of sa d floor and which is capable when the boat is knocked down of lying substantially flat and capable of being bent up to form the sides of the boat. said skin having such mechanical properties that it will assume in the erected boat by virtue of its inherent stiffness curvature as viewed in both plan and elevation at the same place, and said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, and a nose piec on said base member shaped to enter the aperture left by said recess at the bottom of the stem when the boat is erected.

12. A collapsible boat including a skin of springy resilient material capable when the boat is knocked down of lying substantially flat and capable of being bent up to form the sides of the boat, said skin having such mechanical properties that it will assume in the erected boat by virtue of its inherent stiffness curvature as viewed in both plan and elevation at the same place, and said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, a stem post fixed to the inner surface of said skin at each side of said V notch, and means for locking the lower ends of said stem posts together when the boat is erected.

13. A collapsible boat including a rigid longitudinally-extending base member, a skin of springy resilient material which extends laterally from each side of said floor and which is capable when the boat is knocked down of lying substantially flat and capable of being bent up to form the sides of the boat, said skin having such mechanical properties that it will assume in the erected boat by virtue of its inherent stiffness curvature as viewed in both p n a evation at the same place, and said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, a nose piece on said base member shaped to enter the aperture left by said recess at the bottom of the stem when the boat is erected, a stem post fixed to the inner surface of said skin at each side of said V notch, and means for locking the lower ends of said stem posts together when the boat is erected and constituted by a projection on each of said posts positioned to ride on a co-operating element on said nose piece.

14. A collapsible boat including a rigid longitudinally-extending base member, a skin of springy resilient material which extends laterally from each side of said floor and which is capable when the boat is knocked down of lying substantially flat and capable of being bent up to form the sides of the boat, said skin having such mechanical properties that it will assume in the erected boat by virtue of its inherent stiffness curvature as viewed in both plan and elevation at the same place, and said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, a nose piece on said base member shaped to enter the aperture left by said recess at the bottom of the stem when the boat is erected, a stem post fixed to the inner surface of said skin at each side of said V notch, and means for limiting displacement of the lower ends of said posts relative to said base member when the boat is knocked down.

15. A collapsible boat including a rigid longitudinally-extending base member, a skin of springy resilient material which extends laterally from each side of said floor and which is capable when the boat is knocked down of lying substantially flat and capable of being bent up to form the sides of the boat, said skin having such mechanical properties that it will assume in the erected boat by virtue of its inherent stiffness curvature as viewed in both plan and elevation at the same place, and said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, a nose piece on said base member shaped to enter the aperture left by said recess at the bottom of the stem when the boat is erected, a stem post fixed to the inner surface of said skin at each side of said V notch, and a projection extending from the lower end of each of said stem posts substantially longitudinally of the post and positioned to lie, when the boat is'knocked down, closely over a portion of said nose piece, and to ride, as the boat is erected, on a portion of said nose piece so as to lock together the lower ends of said stem posts.

16. A collapsible boat including a rigid longitudinally-extending base member, a skin of springy resilient material which extends laterally from each side of said floor and which is capable when the boat is knocked down of lying substantially fiat and capable of being bent up to form the sides of the boat, said skin having such mechanical properties that it will assume in the erected boat by virtue of its inherent stifiness curvature as viewed in both plan and elevation at the same place, and said skin being provided with V notch the sides of which are capatudinally-extending base member, a skin of springy resilient material which extends laterally from each side of said floor and which is capable when the boat is knocked down of lying substantially flat and capable of being bent up to form the sides of the boat, said skin having such me chanical properties that it will assume in the erected boat by virtue of its inherent stiffness curvature as viewed in both plan and elevation at the same place, and said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, a nose piece on said base member shaped to enter the aperture left by said recess at the bottom of the stem when the boat is erected, and a sealing sheet of rubber overlapping the border of said recess and disposed to be looped under said nose piece on erection of the boat.

18. A collapsible boat including a rigid longitudinally-extending base member, a skin of springy resilient material which extends laterally from each side of said floor and which is capable when the boat i knocked down of lying substantially flat and capable of being bent up to form the sides of the boat, said skin having such mechanical properties that it will assume in the erected boat by virtue of its inherent stiffness curvature as viewed in both plan and eleva" tion at the same place, and said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, a nose piece on said base member shaped to enter the aperture left by said recess at the bottom of the stem when the boat is erected,.a stem post fixed to the inner surface of said skin at each side of said V notch, and a sealing strip of resilient material fixed to each of said stem posts and continuous under said nose piece, said nose piece including a sole portion returned from the forward end thereof under said sealing strip and under the part of said skin that borders the rear of said recess.

19. A collapsible boat including a rigid floor, a

rigid deck frame, a rigid transom hingedly connected to said floor and to said deck frame, a rigid transverse frame disposed in the fore part of the boat and hingedly connected to said floor and to said deck frame, the arrangement being such that said deck frame can be collapsed onto said floor after the manner of a parallel ruler, a skin of resilient material extending laterally from each side of said floor, means mechanical ly connected with said deck frame for straining said skin into the erected position, and means for securing the longitudinal borders of said skin to the longitudinal edges of said deck frame.

20. A collapsible boat including a rigid floor, a rigid deck frame, a rigid transom hingedly connected to said floor and to said deck frame, a rigid transverse frame disposed in the fore part of the boat and hingedly connected to said floor and to said deck frame, the arrangement being such that said deck frame can be collapsed onto said floor after the manner of a parallel ruler, a skin of resilient material extending laterally from each side of said floor, means for securing the longitudinal borders of said skin to the longitudinal edges of said deck frame, a running cable engaging said deck frame and said skin adjacent to said longitudinal borders, and control means for tensioning said cable.

21. A collapsible boat including a substantially fiat rigid floor, a skin of springy resilient material secured to said floor, capable, when the boat is knocked down, of lying substantially flat and also capable of being bent up to form the sides of the hull, two flexible gunwale stringers secured to the longitudinal borders of said skin, a rigid deck frame capable of positioning said sides when the boat is erected, said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat, a rigid transom hingedly connected to said floor and to said deck frame, collapsible means for supporting the forward part of said deck frame from said floor, a running cable disposed in a symmetrical loop one half of said loop passing through a pulley on said skin adjacent to the top of said stem at one side of the boat, thence through a pulley on the border of said skin between the stem and the stern at the other side of the boat, thence through at least one pulley on saiddeck frame on said other side, thence through at least one pulley near the stern corner of said skin on said other side, and thence through at least one pulley on said transom, and control means operable for tensioning said loop.

22. A boat as claimed in claim 21, wherein the fore part of said deck frame is covered with decking, wherein said tensioning means are constituted by a winch drum which is carried by said decking and to which the two ends of said cable loop are anchored, and said cable loop runs freely from side to side of the boat along said transom.

23. A collapsible boat including a rigid longitudinally-extending base member, a skin of springy resilient material secured to said base member, capable, when the boat is knocked down, of lying substantially flat and also capable of being bent up to form the sides of the hull, two flexible gunwale stringers secured to the longitudinal borders of said skin, a rigid deck frame capable of positioning said sides when the boat is erected, means capable, on erection of the boat, of reacting on said skin in the neighbourhood of said gunwale stringers so as to curve them as viewed in plan and at the same time strain the skin inwards into engagement with said deck frame, said skin having such mechanical properties that it will assume in the erected boat a compound curvature by virtue of its inherent stiffness, bolts anchored in said gunwale stringers and projecting from the inner surface of said skin for engagement, on erection of the boat, in locating apertures in said deck frame, and latches on said deck frame serving to anchor said bolts in engagement in said locating apertures.

24. A boat as claimed in claim 23, wherein said latches are self-locking.

25. A collapsible boat including a rigid longitudinally-extending base member, a skin of plywood bonded with synthetic resin secured to said base member, capable, when the boat is knocked down, of lying substantially flat and also capable of being bent up to form the sides of the hull, two flexible gunwale stringers secured to the longitudinal borders of said skin, a transverse bracing member capable of positioning said sides when the boat is erected, and means capable, on erection of the boat, of reacting on said skin in the neighbourhood of said gunwale stringers so as to curve them as viewed in plan and at the same time strain the skin inwards into engagement with said traverse bracing member.

26. A collapsible boat including a skin of plywood bonded with synthetic resin and provided with a v notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, and a sheet 01' flexible sheet metal attached to the outer side of said skin at the stem and at least partly covering said recess.

27. A collapsible boat including a rigid longitudinally-extending base member, a skin of springy resilient material secured to said base member, capable, when the boat is knocked down, of lying substantially flat and also capable of being bent up to form the sides of the hull, said skin having such mechanical properties that it will assume in the erected boat by virtue of its inherent stifiness curvature as viewed in both plan and elevation at the same place, and said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, sheet metal reinforcement which is more flexible than said skin and which is secured to the outer side v of said skin at the stem so as to cover at least part of said recess, a nose piece on said floor capable of being accommodated in the aperture constituted by said recess when the boat is erected, and a sealing strip of rubber attached to the border of said skin at said V notch and continuous across said recess, said nose piece being so shaped that when the boat is erected said rubber strip is nipped in a watertight manner between said sheet metal reinforcement andsaid nose piece.

28. A collapsible boat including a rigid longitudinally-extending base member, a skin 01' springy resilient material secured to said base member, capable, when the boat is knocked down, of lying substantially flat and also capable of being bent up to form the sides of the hull, said skin being provided with a V notch the sides of which are capable of being brought together to form a stem of the boat and the bottom of which merges into a recess, a stem post fixed to the innersurface of said skin at each side of said V notch, sheet metal reinforcement which is more flexible than said skin and which is secured to the outer side of said skin at the stem so as to cover at least part of said recess, a nose piece on said floor capable of being accommodated in the aperture constituted by said recess when the boat is erected, and a sealing strip of rubber attached to the inner faces of said stem posts and continuous across said recess, said nose piece being so shaped that, when the boat is erected, the portions of said rubber strip that are on said stem posts are pressed together, while the middle portion of the length of said rubber strip is nipped between said sheet metal reinforcement and said nose piece. FRANCIS BRIAN SYLVESTER GRIMSTON. 

